Volume 36, Issue 1, 2017

Pallid bat

A tough bat who defies the rules

A pallid bat (Antrozous pallidus) munches on a scorpion Courtesy of Richard Jackson

The pallid bat (Antrozous pallidus) is an impressively tenacious bat, thanks in no small part to its penchant for wrestling and consuming scorpions. As the sole species of the genus Antrozous; the pallid bat can be found from south-central British Columbia to central Mexico and Cuba.

With its large ears and pig-like nose, the pallid bat may look a bit goofy. But these adaptions are key to the bat’s ground gleaning hunting behavior. In conjunction with echolocation, the pallid bat will passively listen for the sounds made by their prey—large beetles, Jerusalem crickets and other large arthropods—scuttling along on the ground. Once the prey is detected, the bat will land and attack the prey on the ground. The resulting tussle may result in a few bites or stings to the bat, but the species appears to be immune to the venom of scorpion stingers.

Bat Conservation International’s Senior Director of Conservation Science, Winifred Frick, Ph.D., has observed the pallid bat exhibiting another unusual behavior; it will drink cactus nectar when available. The converse—nectarivorous or frugivorous bats in the tropics consuming insects for their protein—is known to occur, but this unique opportunistic behavior of an insectivorous bat supplementing its diet with nectar is only observed in one other bat species located in New Zealand.

“Discovering that pallid bats love to drink cactus nectar has been one of the highlights of my scientific work, I think in part because it was a really fun natural history discovery that we made by just being out in the Sonoran Desert in Baja California at night and being observant. We were trying to see if we could watch lesser long-nosed bats drinking cactus nectar and all of a sudden we noticed that the bats landing on the flowers had big ears and a tail membrane and were not hovering the way lesser long-nosed bats do. They were pallid bats! After that first awestruck night, we set up cameras and almost everywhere we went in the desert in Baja California, Mexico, we could watch pallid bats coming to drink cactus nectar at night. We now know they also eat the fruit of the cactus and we’ve observed them actually crawling inside the fruit husk to get a fruit snack.”

A pallid bat (Antrozous pallidus) on a cardon cactus flower Courtesy of MerlinTuttle.org

Since the pallid bat does not possess any morphologic adaptions for nectar eating (long tongue, long muzzle, etc.), it must plunge its whole head and torso into the flower to obtain the nectar. This results in more pollen attaching to its fur. Consequently, the bat will deliver more pollen to the stigmas each visit, making it a more effective pollinator per flower visit than the lesser long-nosed bat (the primary pollinator of the cardon cactus).

“Pallid bats are by far my favorite species of bat. The most obvious reason is that they are tough and can tackle and eat a scorpion but they also have this goofy side to their look and personality. I’ve worked with them a few times in a flight cage and they quickly show different personalities and get tame right away, which amazes me,” explains Frick.

Pallid bats are gregarious and will roost in colonies between 20 and several hundred individuals. They typically roost in rock crevices, but they can also be found in attics, barns, caves and under bridges. The pallid bat will night-roost by locating a place that is warm from the latent heat of the day and eat prey caught while flying or swap social information with other members in the colony.

Females will form maternity colonies to raise their young together. These colonies are typically small, with populations around 20 or so individuals. Each mother will give birth to one pup in May or June and the pup will stay with the mother until it can fly—usually within five to six weeks.

Though the pallid bat is common throughout most of its range, it is particularly sensitive to human disturbance of roosting areas and foraging grounds. We must remember to tread lightly so that these remarkable bats can thrive.